Igniter for oil burners



Jan. 28, 1941. K. P. BRACE ET A1. 2,229,717

IGNITER FOR OIL BURNERS Filed March 14, 1938 Patented Jan. 28, 1941IGNITER FOR OIL BURNERS Kemper P. Brace and Franklin H. Wells, SouthBend, Ind., assignors to International Engineering Corporation,AChicago, Ill., a corporation of Illinois Application March 14, 1938,Serial No. 195,770

7 Claims.

This invention relates to oil burners and similar devices, and moreparticularly to ignition means therefor.

An object of the invention is to provide a hotwire ignition device whichwill vaporize and ignite the fuel with a minimum input of electricalenergy. Another object is to so locate the igniter that after ignitionis effected the igniter itself will be entirely outside the zone ofburning of lo the fuel and consequently will not be subjected toextremely high temperatures, and so that the electrical connectionsthereto will not be subject to high temperatures, and preferably also sothat the igniter is shielded from the direct fiow of air for combustion.Another and very important object is to provide a very effective form ofhot-wire igniter using a relatively small current and which quicklyreaches a high temperature when the ignition current is passedtherethrough.

The igniter, in the form illustratedin the drawing, comprises aresistance wire wound to form a relatively long small-diameter innercoil encircled by a relatively short large-diameter outer coil, and isarranged in the rear end of an air passage approximately at the centerof a porous refractory member to which the fuel is fed, and throughwhich the fuel seeps transversely of a series of such air passages.

'I'hus initial ignition takes place after the oil has traveled farenough to give time for the igniter to heat up and yet far enough fromthe bottom of the porous member so that no fuel is lost by dripping fromits lower surface before combustion starts. Moreover ignition takesplace Well behind the zone in which combustion takes place after theburner gets started. Preferably a shield is placed just behind theigniter, to insure turbulence of the fuel-air mixture dur- 0 ingignition, and to shield the igniter from the direct iiow of airthereafter.

The above and other objects and features of the invention will beapparent from the following description of the illustrative embodimentshown in the accompanying drawing, in which:

Figure 1 is a central vertical section longitudinally through the burneras it appears when mounted in a furnace; and

Figure 2 is a side elevation, .on a larger scale,

of theigniter proper.

Tests of hot-wire igniters, for oil burners and the like, have shownthat with a given length and size of wire and with a given current inputthe manner in which the wire is coiled or other- Q# Wise arranged has avery great effect on its temone of the upper passages I4.

perature, and consequently on its effectiveness in igniting the oil. Ina single coil the most effective arrangement is in a coil of substantialdiameter whose length is approximately equal to its diameter. 5

We provide such a coil I0, of suitable resistance wire; we nd, however,that we can greatly increase its effectiveness by arranging it toencircle a relatively long small-diameter inner coil I2. Preferably thetwo coils are integral, being 10 wound from the same resistance wirewith the outer coil arranged centrally of the inner coil, as shown inFigure 2. Since the inner coil is radiating to a hot outer coil, andreceives heat from the outer coil, it as well as the outer coil l5becomes very hot and is very effective.

The igniter is arranged at the rear end of one of a plurality of airpassages I4 through and paralleling the axis of a porous refractorymember I6, the igniter being approximately at the 20 center of its rearface. The illustrated porous member I6 is formed with a convex frontface and a substantially plane rear face, with the passages I4paralleling its axis.

Fue1 is supplied to the upper part .of member 25 I6 by means such as aspout I8 having a removable cleanout plug 20 and discharging into Thespout I8 receives oil fuel through a conduit 22, fed by gravity or by asuitable pump, under the control of 30 a fuel valve (not shown)controlled by the usual room thermostat (not shown). The fuel seepsdownwardly through the porous structure of member I6, transversely ofthe passages I4.

The member I6 is secured, by means such as 35 a holding ring 24, in thefront end of a generallycylindrical open-ended carrier 26. The carrier26 is flanged outwardly at its rear end and secured (by suitablefastenings) to the rear end of acasing 28 formed to be seated in thefuel 40 door or other opening in the side wall of a furnace, a suitablerefractory panel 30 closing the remainder of the opening. The front endof the casing is shown conical, so that in a general way it parallelsthe front face of the member I6. 45 The whole burner is mounted todischarge into the furnace at a slight angle downwardly.

Excess fuel, in the case of ignition failure for example, may drain backthrough a conduit 32 to-operate a suitable iioat-type safety shut-olf 50switch (not shown).

If desired, the conduit 32 may also be utilized as a housing for anignition wire 34 connected to a binding screw 36 passing through aninsulating bushing 38 to a heavy wire support 40, 55

The support 4l) and a similar support 42 grounded on the carrier 213 arewelded or otherwise secured to the ends of the resistance Wire making upthe coils ill-l2, and support the igniter as Well as supply currentthereto When the room thermostat calls for heat.

A shield 44, preferably of mica or other transparent refractorymaterial, may be mounted on the ends of the resistance Wire, a shortdistance behind the rear face of the member i6.

The flow of air through the burner, under the influence of the suctionfrom the chimney of the furnace, is controlled by a glass or othertransparent heini-spherical closure 4G having a central stem 48adjustably threaded into a nut 50 secured to a diametrically-arrangedvertical bar 52 Welded at its ends to the flanged rear end of carrier26.

It will be seen that, when the igniter is first energized, the flow ofair through the burner is slow as compared to the ilo-W after the burneris in operation. When the fuel `seeps down far enough to reach thepassage containing the igniter, the heat therefrom vaporiaes and thenignites a small part of the fuel. rlhe air ilow through the burneralmost immediately reaches such a velocity that the zone of combustionis just in front of the member It and in the front ends of the passagesle, leaving the igniter lill2 and its connections it-i2 entirely behindthat zone. rilhe shield riti, if used, insures turbulence of thefuel-air mixture about the coils Il'l-lt during ignition, and alsoprotects the igniter from the direct flow of air after ignition When theflow becomes more rapid.

Since the closure it and the shield i4 are transparent, the operation ofthe igniter and of the burner can conveniently be observed at any time.-

Except for our improvements in the construction and arrangement of theigniter, the illustrated burner is covered by applications Nos. 145,706and 195,769, filed respectively June 1, 1937, and March 14, 1938, byKemper P. Brace, and is not claimed herein.

While one illustrative embodiment has been described in detail, it isnot our intention to limit the scope of the invention to that particularembodiment, or otherwise than by the terms of the appended claims.

We claim:

1. A11 oil burner comprising an open-ended casing adapted to be mountedin an opening in the side Wall of a furnace, a porous refractory membersupported at the front end of the casing and which is formed with airpassages therethrough generally paralleling the axis of the casing,means at the rear end of the casing for varying the air flow through thecasing, a hot- Wire igniter supported in the rear end of one of said airpassages approximately in the central plane of said member and whichincludes a rei sistance Wire formed to provide a small diameter innerresistance coil encircled by a large diameter outer resistance coil, andmeans for supplying liquid fuel to said member to seep therethroughtransversely of said passages.

2. An oil `burner comprising an open-ended casing adapted to be mountedin an opening in the side Wall of a furnace, a porous refractory membersupported at the front end of the casing and Which is formed with -airpassages therethrough generally paralleling the axis of the casing,means at the rear end of the casing for varying the air flow through thecasing, a hot-Wire igniter supported in the rear end of one of said airpassages which includes a resistance Wire formed to provide a smalldiameter inner resistance coil encircled by a large diameter outerresistance coil, a shield mounted behind said igniter and spaced fromthe rear side of said member, and means for supplying liquid fuel tosaid member to seep therethrough transversely of said passages.

3. An oil burner comprising an open-ended casing adapted to be mountedin an opening in the side wall of a furnace, a porous refractory membersupported at the front end of the casing and Which is formed With airpassages therethrough generally paralleling the axis of the casing,means at the rear end of the casing for varying the air flow through thecasing, a hot-Wire igniter supported in the rear end of one of said airpassages, a shield mounted behind said igniter and spaced from the rearside of said member, and means for supplying liquid fuel to said memberto seep therethrough transversely of said passages.

4. An oil burner comprising a porous refractory member having a convexfront face and a generally plane rear face and formed with air passagestherethrough, means to supply liquid fuel to said member to seep throughthe structure thereof transversely of said air pasages, a hot wireigniter in the rear end of one of the air passages and which consists ofa resistance Wire formed to provide a relatively small diameter innercoil encircled by a relatively large diameter outer coil, and a shieldspaced a short distance behind the igniter opposite the central portionof the rear face of said member.

5. An oil burner comprising a porous refractory member having a convexfront face and a generally plane rear face and formed with air passagestherethrough, means to supply liquid fuel to said member to seep throughthe structure thereof transversely of said air passages, a hot Wireigniter in the rear end of one of the air passages, and a shield spaceda short distance behind the igniter opposite the central portion of therear face of said member.

6. An oil burner comprising a porous refractory member formed with airpassages therethrough, means to supply liquid fuel to said member toseep through the structure thereof transversely of said air passages, ahot Wire igniter in the rear end of one of the air passages and whichconsists of a resistance Wire formed to provide a relatively smalldiameter inner coil encircled by a relatively large diameter outer coil.

7. An oil burner comprising a porous refractory member formed with airpassages therethrough, means to supply liquid fuel to said member toseep through the structure thereof transversely of said air passages, ahot Wire igniter in the rear end of one of the air passages and whichconsists of a resistance Wire formed to provide a relatively smalldiameter inner coil encircled by a relatively large diameter outer coil,and a shield spaced a short distance behind the igniter opposite thecentral portion of the rear face of said member.

KEMPER P. BRACE. FRANKLIN H. WELLS.

